New Born baby Girl. Bottle with nipple?

My baby girl is 1 month old and she is taking formula milk mostly because my wife's not getting enough breast milk. Now sometimes my baby doesn't even want to take formula and cries a lot. We are giving formula milk with spoon.She kind of keep searching for Breast milk. She doesn't have any fix routine of taking milk. She gets hungry very frequently. We are worried that as there is no such routine of her she is not getting enough and is hungry again. and it can hinder her growth. her birth weight was 3.1 KG and after month its 3.3KG. Is it normal with new born ? We asked the doctor and she said its normal. We are not convinced with that? can u pls suggest if its normal and do we need to do something so takes enough milk?.Should we try to give her milk using bottle with nipple?